This invention relates to electric motors, and in particular to the position sensorless control of electric motors.
It is known to use motor control methods that use an algorithm to estimate the motor position rather than using a position sensor. However, many of these sensorless algorithms do not operate well at low motor speeds. Those that can operate at low or zero speeds are significantly more complex than those that only operate at higher speeds. However in some applications, such as fans and pumps, including hydraulic pumps for power steering systems, there is a need to produce relatively low cost systems that avoid the cost of a position sensor and the complication of known zero speed position determining algorithms.